1. Technical Field
The present invention relates to a tongue assembly for use in a vehicle seat belt system for restraining movement of an occupant of a vehicle.
2. Description of the Prior Art
A known vehicle seat belt system is a three-point continuous loop seat belt system. A three-point continuous loop seat belt system includes a seat belt retractor and a length of belt webbing. The belt webbing extends from the retractor through a D-ring fixed to the vehicle and then down to an anchor point near the vehicle floor. A tongue assembly is slidable along the length of belt webbing between the D-ring and the anchor point. To use the seat belt system, a vehicle occupant grasps the tongue assembly and inserts it into a buckle on the opposite side of the vehicle seat from the anchor point. When the tongue assembly is fastened in the buckle, a portion of the belt webbing extends across the lap of the vehicle occupant and a portion of the belt webbing extends diagonally across the torso of the vehicle occupant.
When the tongue assembly is released from the buckle, the belt webbing is wound onto the retractor. As the retractor winds the belt webbing, the tongue assembly may be moved along with the belt webbing. The tongue assembly may engage the D-ring before the belt webbing is completely stowed on the retractor. If the belt webbing cannot be pulled freely through the tongue assembly when the tongue assembly engages the D-ring, belt retraction stops, and some belt webbing is left loose and unretracted. Accordingly, it is desirable for a tongue assembly to allow the belt webbing to run freely through the tongue assembly when the tongue assembly is adjacent a D-ring.
A three-point continuous loop seat belt system may sometimes be used to secure a child seat, rather than a vehicle occupant, on the vehicle seat. In such a case, the lap portion of the belt webbing holds the child seat on the vehicle seat. The seat belt system must be placed in a condition so that the lap portion of the belt webbing cannot be lengthened, in order to hold the child seat securely in position on the vehicle seat.
If the tongue assembly does not itself clamp the lap portion of the belt webbing, a known child clip can be placed on the belt webbing at a location separate from the tongue assembly. The lap and torso portions of the belt webbing are threaded through the child clip. The child clip blocks movement of the lap and torso portions of the belt webbing through the child clip, and thus the tongue assembly, thereby securing the child seat on the vehicle seat.
Since a child clip is a separate piece from the remainder of the seat belt system, it is easy to lose the child clip. Also, if the child clip is inadvertently not placed on the belt webbing when the seat belt system is to be used for restraining movement of a child seat, then the child seat is not fully secured by the seat belt system. Accordingly, it is desirable that a tongue assembly be capable of blocking movement of the belt webbing through the tongue assembly when it is desired to secure a child seat.